The present invention relates to microelectromechanical systems (MEMS) technologies.
A considerable amount of development has taken place recently in the use of diamond for MEMS devices. For instance, xe2x80x9cDiamond MEMO-A New Emerging Technologyxe2x80x9d by E. Kohn et al., Diamond and Related Materials 8 (1999) 934940, discusses the use of diamond and for electromechanical devices and their integration with driver or signal conditioning circuits. The article discloses chemical vapor deposition (CVD) films on large area substrates and also discloses the use of nanocrystalline, randomly oriented films when CVD diamond films ha been deposited on insulating substrates like silicon dioxide. However, there has to be substantial pretreatment of the silicon dioxide in order to deposit diamond films. Accordingly, the use of diamond films on silicon dioxide and silicon substrates has not enjoyed the wide spread use envisioned.
Another article relating to the general subject matter appeared in Thin solid films. by Raleshuni Reanesham entitled xe2x80x9cFabrication of Diamond Microstuctures For Micoetromechanol Systems (MEMS) by a Surface Micmachining Processxe2x80x9d, Thin Solid Films 340(1999) 1-6. In this article, various methods of depositing polycrystalline diamond films on silicon dioxide/silicon substrates are reported including a variety of pretreatment methods including ultrasonically damaging the surface or etching the surface, prior to film deposition. The article describes methods in which the silicon dioxide surface on which the diamond was to be deposited was pretreated including damaging the surface by ultrasonic agitation either for the entire surface or patterned portions of the surface. These methods have heretofore been required in order to deposit diamond on silicon and silicon dioxide surfaces.
Another aspect of the problem encountered in the use of diamond films for MEMS devices is reported in the article xe2x80x9cHigh Nucleation Density For Growth of Smooth Diamond Filmsxe2x80x9d by Yang et al. in the Applied Phys. Letter Vol. 66, No. 316January 1995, pgs. 311-313. These papers generally show the state of the art of applying diamond films to MEMS devices, which require substantial pretreatment of the silicon or silicon dioxide substrate prior to depositing diamond film thereon.
Accordingly, it is an object of the present invention is to provide a superior diamond film for use in MEMS devices and to the formation of ultrananocrystalline diamond films on silicon dioxide and other oxide substrates and for the patterning of these films for producing MEMS devices.
Another object of the present invention is to provide a method of depositing ultrananocrystalline films of the type disclosed in U.S. Pat. No. 5,989,511 issued to Gruen et al. Nov. 23, 1999, the entire disclosure of which is incorporated herein by reference as well as films prepared according to the teachings of U.S. Pat. No. 5,620,512 issued to Gruen et al. Apr. 15, 1997, and U.S. Pat. No. 5,772,560 issued to Gruen et al. Jun. 30, 1998, the entire disclosures of each of the above named patents being incorporated herein by reference.
The ultrananocrystalline films taught in the above-identified patents can be directly deposited on oxide substrates without pretreatment thereof and an object of this invention is to provide a method for depositing ultrananocrystalline films directly on oxide substrates without the necessity of pretreating the oxide substrates.
Another object of the present invention is to provide a method of fabricating structures in which a carbon dimer species is contacted directly with an oxide substrate forming a carbide layer on the surface onto which ultrananocrystalline diamond having average grain sizes of less than 10 nanometers is deposited permitting feature resolution of less than about 1 micron using known microfabrication processes.
Another object of the present invention is to provide a microelectromechanical (MEMS) structure formed at least in part from ultrananocrystalline diamond films having average grain sizes of less than about 10 nanometers and feature resolution of less than about 1 micron.
Another object of the present invention is to provide a method of fabricating free standing nanocrystalline MEMS structures having feature resolution of 1 micron or less which a hard mask material is deposited over the diamond film and a pattern is formed over the hard mask material followed by etching the exposed hard mask to expose selected areas of the diamond film and thereafter removal of the exposed diamond film to form the diamond pattern.
Another object of the present invention is to provide a method which includes removal of the substrate and remaining hard mask material to produce free standing structures of ultrananocrystalline diamond film useful in MEMS devices.
The invention consists of certain novel features and a combination of parts hereinafter fully described, illustrated in the accompanying drawings, and particularly pointed out in the appended claims, it being understood that various changes in the details may be made without departing from the spirit, or sacrificing any of the advantages of the present invention.